Two-year optical site characterization for the Pacific Ocean Neutrino Experiment (P-ONE) in the Cascadia Basin

The STRings for Absorption length in Water (STRAW) are the first in a series of pathfinders for the Pacific Ocean Neutrino Experiment (P-ONE), a future large-scale neutrino telescope in the north-eastern Pacific Ocean. STRAW consists of two $$150\,\mathrm {m}$$ 150 m long mooring lines instrumented with optical emitters and detectors. The pathfinder is designed to measure the attenuation length of the water and perform a long-term assessment of the optical background at the future P-ONE site. After 2 years of continuous operation, measurements from STRAW show an optical attenuation length of about 28 m at $$450\,\mathrm {nm}$$ 450 nm . Additionally, the data allow a study of the ambient undersea background. The overall optical environment reported here is comparable to other deep-water neutrino telescopes and qualifies the site for the deployment of P-ONE.

The mini-JPAS: A Study of the Wavelength Dependence of the Photon Response Nonuniformity of the JPAS-Pathfinder Camera

Understanding the origins of small-scale flats of CCDs and their wavelength-dependent variations plays an important role in high-precision photometric, astrometric, and shape measurements of astronomical objects. Based on the unique flat data of 47 narrowband filters provided by JPAS-Pathfinder, we analyze the variations of small-scale flats as a function of wavelength. We find moderate variations (from about 1.0% at 390 nm to 0.3% at 890 nm) of small-scale flats among different filters, increasing toward shorter wavelengths. Small-scale flats of two filters close in central wavelengths are strongly correlated. We then use a simple physical model to reproduce the observed variations to a precision of about ±0.14% by considering the variations of charge collection efficiencies, effective areas, and thicknesses between CCD pixels. We find that the wavelength-dependent variations of the small-scale flats of the JPAS-Pathfinder camera originate from inhomogeneities of the quantum efficiency (particularly charge collection efficiency), as well as the effective area and thickness of CCD pixels. The former dominates the variations in short wavelengths, while the latter two dominate at longer wavelengths. The effects on proper flat-fielding, as well as on photometric/flux calibrations for photometric/slitless spectroscopic surveys, are discussed, particularly in blue filters/wavelengths. We also find that different model parameters are sensitive to flats of different wavelengths, depending on the relations between the electron absorption depth, photon absorption length, and CCD thickness. In order to model the wavelength-dependent variations of small-scale flats, a small number (around 10) of small-scale flats with well-selected wavelengths are sufficient to reconstruct small-scale flats in other wavelengths.

Nuclear Radiation Shielding Characteristics of Some Natural Rocks by Using EPICS2017 Library

Radiation leakage is a serious problem in various technological applications. In this paper, radiation shielding characteristics of some natural rocks are elucidated. Mass attenuation coefficients (µ/ρ) of these rocks are obtained at different photon energies with the help of the EPICS2017 library. The obtained µ/ρ values are confirmed via the theoretical XCOM program by determining the correlation factor and relative deviation between both of these methods. Then, effective atomic number (Zeff), absorption length (MFP), and half value layer (HVL) are evaluated by applying the µ/ρ values. The maximum μ/ρ values of the natural rocks were observed at 0.37 MeV. At this energy, the Zeff values of the natural rocks were 16.23, 16.97, 17.28, 10.43, and 16.65 for olivine basalt, jet black granite, limestone, sandstone, and dolerite, respectively. It is noted that the radiation shielding features of the selected natural rocks are higher than that of conventional concrete and comparable with those of commercial glasses. Therefore, the present rocks can be used in various radiation shielding applications, and they have many advantages for being clean and low-cost products. In addition, we found that the EPICS2017 library is useful in determining the radiation shielding parameters for the rocks and may be used for further calculations for other rocks and construction building materials.

Determination of Absorption Lengths using PWP Model in the Bay of Bengal

<p>In this study, we model the upper layers of the Bay of Bengal, which is rather a unique water body in terms of its dynamics which is controlled by the advection of large fresh water from the adjoining rivers as well monsoonal precipitation thus changing the turbulent mixing in the upper layers. The fresh water influx from rivers and precipitation, leads to low saline water overlying hypersaline water, creates a strong stratification due to which turbulent mixing is inhibited. The resulting halocline inhibits the wind driven mixing of the upper layers thus changing or affecting the optical characteristics of the water body. With the exception of shortwave insolation, the air – sea heat exchange occurs at the sea surface and is vertically redistributed by mixing and advection. The present study focuses on generating these optical or absorption lengths (e-folding depths) at different locations in the Bay of Bengal as a function of time itself, showing absorption length changes with both the space and the time, using the PWP – 1D model for which data is obtained from RAMA Buoys located along 90<sup>0</sup>E in the Bay of Bengal. The shortwave and longwave absorption length is directly related to heating up of the upper layers of the ocean and thus change its state and dynamics. Heating of the upper oceanic layers are also related to increase in SST as well as the Ocean Heat content of the ocean leading to changes in various systems like monsoon, cyclones, fluxes, etc. These absorption lengths are related to the Mixed layer heat budget directly but it may also be related to the salt budget of the Bay too. The model results highlight that the absorption length affects the SST as well as the temperature of the upper layers and also that the absorption length changes from one season to another season done using the data of - RAMA Buoy located at 90<sup>0</sup>E and 15<sup>0</sup>N (northern Bay of Bengal) and 90<sup>0</sup>E and 12<sup>0</sup>N as well as data from INCOIS tropflux. The study encourages to use the generated results for the Mixed layer heat budget analysis, or for the modelling purpose, etc.</p><p> </p><p><strong>Keywords - </strong>Bay of Bengal, Mixing in the upper layers, Absorption lengths, extinction lengths, Penetration depths, E-folding depth, RAMA buoy, Solar insolation, Water type and quality, Sea surface temperature, PWP – 1D model, Seasonality.</p>

Sensitivity to losses and defects of the symmetry-induced transmission enhancement through diffusive slabs

We inspect the robustness to absorption and to symmetry defects of the symmetry-induced broadband enhancement through opaque barriers in disordered slabs. The sensitivity of this phenomenon to symmetry defects is found to be strongly related to the distance from to barrier to the nearest defect, and, following, we propose a probabilistic model to estimate the conductance of a medium with an arbitrary number of randomly distributed defects. Also, the conductance enhancement is shown to be robust to absorption in the disordered medium, though being of course weakened. For sufficiently opaque barriers, the conditions of an optimal enhancement are mainly driven by the absorption length of the medium.

Analytical investigation of wave absorption by a rotating black hole analogue

Perturbations in a draining vortex can be described analytically in terms of confluent Heun functions. In the context of analogue models of gravity in ideal fluids, we investigate analytically the absorption length of waves in a draining bathtub, a rotating black hole analogue, using confluent Heun functions. We compare our analytical results with the corresponding numerical ones, obtaining excellent agreement.

State of Art of Thin Film Photovoltic Cell: A Review

The latest progress and future perspectives of thin-film photovoltaic technology are reviewed herein. This paper reviews the two thin-film solar cell technologies copper indium gallium selenide (CIGS), and cadmium telluride (CdTe) and their parameter affecting them. Thin-film solar cell offers a variety of choices in term of device design, tunable property (lifetime, absorption length, conductivity) and verity substrate. Proper understanding of thin-film photovoltaic cells under various parameters like temperature, bandgap, conversion efficiency, open-circuit voltage, and short circuit current, fill factor, and thickness.

Monitoring Ambient Nitrate Radical by Open Path Cavity Enhanced Absorption Spectroscopy

<p>We described an open-path cavity enhanced absorption spectroscopy (OP-CEAS) technique for ambient measurement of nitrate radical (NO<sub>3</sub>) near 662 nm. Compared with the close type CEAS system with a sampling line, the OP-CEAS is featured with high accuracy due to free of quantifying NO<sub>3 </sub>loss in the sampling line and cavity. Based on a 0.84 m long open path cavity, the effective absorption length of ~5 kilometers is achieved by a coupled high reflectivity mirrors with the reflectivity of 0.99985 at 662 nm. The detection limit of OP-CEAS for NO<sub>3</sub> measurement is 3.0 pptv (2σ) in 30 seconds. The uncertainty is 11.2% and dominated by the cross section of NO<sub>3</sub>. The instrument was successfully applied in a field measurement at low particulate matter (PM) loading condition. As the sensitive would be decreased due to the strong PM extinctions under heavy PM pollution condition, we highlight the feasibility of this OP-CEAS configuration in the field application under the low PM condition, such as the forest region affected by anthropogenic emissions. This technique also appropriates to be expended in the field detection of other reactive trace gases in future studies.</p>

Analytical Study on Pulsed-Laser Processing for Acrylonitrile Butadiene Styrene/ PolyVinyl Chloride

This study developed a model involving the energy balance and decomposition at the ablated interface due to the heat transport, optical decomposition and activation energy in Acrylonitrile Butadiene Styrene/PolyVinyl Chloride (ABS/PVC). The prediction for ablation depth obtained from this study is compared with the available experimental data. The predicted results agree with the measured data. The effects of laser processing parameters, optical and thermal properties of ABS/PVC on the variation of the laser-ablated depth with the laser fluences are also discussed. The results validate that the pulsed-laser ablation rate at the initial short period is dominated by optical penetration absorption for laser and is linearly proportional to the logarithm of the laser fluence by a ratio factor “optical absorption length” (i.e., the ablation rate follows Beer’s law at the initial short period).